feat: paginate list views, fix stale page titles, tidy admin filter bar

Bundle of small UI/UX fixes plus a build hygiene tweak.

* List pagination — Home (`/`) and `/authors/[id]` silently capped at
  the backend default of 50 with no UI to advance. New reusable
  `Pager.svelte` (Prev/Next + numbered with ellipsis), URL-synced
  `?page=N`, and filter/search/sort reset to page 1 so users aren't
  stranded on an out-of-range page. Count label now shows a range
  ("Showing 51–100 of 237").

* Stale page title — Pages without a `<svelte:head><title>` left the
  document title at whatever the last manga / author / collection page
  set it to. Move static-route titles into a route-id → title map in
  the root layout and invert every dynamic title to brand-first
  (`Mangalord | {X}`) for consistency.

* Admin filter bar — `/admin/mangas` search input had `flex: 1` and
  ballooned across the row, shoving the sync-state select + Search
  button to the far right. Cap at 24rem, vertical-align the row, and
  promote the previously aria-only "Sync state" label to visible text.

* Build hygiene — `backend/target` had grown to 68 GiB. Cleaned and
  added `[profile.dev] debug = "line-tables-only"` (and `[profile.test]`
  too) to cut future dev builds by ~50–70% while keeping line numbers
  in backtraces.

Also: configure vitest to resolve Svelte's browser entry so
`@testing-library/svelte` can mount components in jsdom — needed for
the new `Pager.svelte.test.ts`.

Bump 0.48.0 -> 0.49.1.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/e2e/manga-list.spec.ts

@@ -10,6 +10,15 @@ import { test, expect, type Page } from '@playwright/test';
 const emptyPage = { items: [], page: { limit: 50, offset: 0, total: null } };
 
 async function mockAnonymous(page: Page) {
+    // Force public mode so the root +layout.ts doesn't bounce us to /login
+    // (a dev backend with PRIVATE_MODE=true must not leak into E2E runs).
+    await page.route('**/api/v1/auth/config', async (route) => {
+        await route.fulfill({
+            status: 200,
+            contentType: 'application/json',
+            body: JSON.stringify({ self_register_enabled: true, private_mode: false })
+        });
+    });
     await page.route('**/api/v1/auth/me', async (route) => {
         await route.fulfill({
             status: 401,
@@ -69,3 +78,53 @@ test('search updates the manga list', async ({ page }) => {
     await expect(page.getByTestId('manga-list')).toContainText('Berserk');
     expect(lastSearch).toBe('berserk');
 });
+
+test('clicking Next paginates to page 2 and updates the URL', async ({ page }) => {
+    await mockAnonymous(page);
+
+    // Fake a catalogue of 75 mangas; page 1 is ids 1..50, page 2 is ids 51..75.
+    const TOTAL = 75;
+    function mangaAt(i: number) {
+        return {
+            id: `m${i}`,
+            title: `Manga ${i}`,
+            author: 'Test',
+            description: null,
+            cover_image_path: null,
+            created_at: '2026-01-01T00:00:00Z',
+            updated_at: '2026-01-01T00:00:00Z',
+            authors: [],
+            genres: []
+        };
+    }
+
+    await page.route('**/api/v1/mangas*', async (route) => {
+        const url = new URL(route.request().url());
+        const limit = Number(url.searchParams.get('limit') ?? '50');
+        const offset = Number(url.searchParams.get('offset') ?? '0');
+        const items: ReturnType<typeof mangaAt>[] = [];
+        for (let i = offset + 1; i <= Math.min(offset + limit, TOTAL); i++) {
+            items.push(mangaAt(i));
+        }
+        await route.fulfill({
+            status: 200,
+            contentType: 'application/json',
+            body: JSON.stringify({
+                items,
+                page: { limit, offset, total: TOTAL }
+            })
+        });
+    });
+
+    await page.goto('/');
+    await expect(page.getByTestId('manga-total')).toContainText('Showing 1–50 of 75');
+    await expect(page.getByTestId('manga-list')).toContainText('Manga 1');
+    await expect(page.getByTestId('manga-list')).not.toContainText('Manga 75');
+
+    await page.getByTestId('manga-pager').getByRole('button', { name: /next/i }).click();
+
+    await expect(page).toHaveURL(/[?&]page=2(&|$)/);
+    await expect(page.getByTestId('manga-total')).toContainText('Showing 51–75 of 75');
+    await expect(page.getByTestId('manga-list')).toContainText('Manga 75');
+    await expect(page.getByTestId('manga-list')).not.toContainText('Manga 1');
+});